Question 1202786
<font color=black size=3>
You have the correct dot product of -1.


The computation for ||u|| is incorrect. It should be 5 instead of {{{sqrt(5)}}}


The computation for ||v|| is correct. 


cos(theta) = ( u dot v )/( ||u||*||v|| )
cos(theta) = ( -1 )/( 5*sqrt(41) )
cos(theta) = -0.03123475237772
theta = arccos(-0.03123475237772)
theta = 91.789910608246 degrees


The result is approximate. Round it however needed.
The answer can be confirmed with GeoGebra.
</font>